View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Clemson University: TigerPrints Clemson University TigerPrints All Theses Theses 5-2015 Finding the Needle and the Haystack: New Insights into Locating Bog Turtles (Glyptemys muhlenbergii) and their Habitat in the Southeastern United States Theresa Sonja Margareta Stratmann Clemson University Follow this and additional works at: https://tigerprints.clemson.edu/all_theses Part of the Aquaculture and Fisheries Commons, and the Biology Commons Recommended Citation Stratmann, Theresa Sonja Margareta, "Finding the Needle and the Haystack: New Insights into Locating Bog Turtles (Glyptemys muhlenbergii) and their Habitat in the Southeastern United States" (2015). All Theses. 2176. https://tigerprints.clemson.edu/all_theses/2176 This Thesis is brought to you for free and open access by the Theses at TigerPrints. It has been accepted for inclusion in All Theses by an authorized administrator of TigerPrints. For more information, please contact [email protected]. FINDING THE NEEDLE AND THE HAYSTACK: NEW INSIGHTS INTO LOCATING BOG TURTLES (GLYPTEMYS MUHLENBERGII) AND THEIR HABITAT IN THE SOUTHEASTERN UNITED STATES A Thesis Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Master of Science Wildlife and Fisheries Biology by Theresa Sonja Margareta Stratmann May 2015 Accepted by: Dr. Kyle Barrett, Committee Chair Dr. Robert Baldwin Dr. Michael Dorcas i ABSTRACT Because rare and cryptic species can be difficult to locate, distribution maps for these species are often inaccurate or incomplete. Bog Turtles (Glyptemys muhlenbergii) are emblematic of this challenge. In fact, conducting surveys of known, historical, and potential Bog Turtle habitat is a specific need stated in the Bog Turtle Northern Population Recovery Plan and in most Comprehensive Wildlife Conservation Strategies of states within the southern range. Therefore we examined ways to better locate Bog Turtle habitat and Bog Turtles within that habitat. First we determined a detection probability for a standardized trapping method so we could effectively survey for Bog Turtles at sites with unknown occupancy status. A species distribution model (SDM) was then used to identify potentially suitable Bog Turtle habitat within the species’ southern range. The SDM was ground-validated, using our trapping method, to assess its ability to locate suitable Bog Turtle habitat. At a local scale we then analyzed wetlands occupied and unoccupied by Bog Turtles to examine differences in their habitat characteristics and site history. We had a 0.19 average probability of detecting a turtle at a site during one trapping event, implying 15 trapping events at a site would minimize the probability of Bog Turtles being at a site but going undetected to 5%. Ground-validation of the SDM with this trapping method showed that the SDM greatly over-predicted the amount of suitable habitat. For example, of 196 wetlands in Georgia and South Carolina identified as suitable by the SDM and ground-validated, only 22 met criteria for suitable Bog Turtle habitat, and trapping of 17 of those suitable wetlands revealed only 2 to be occupied by Bog Turtles. At the local scale, a discriminant analysis showed that wetlands with Bog ii Turtles were distinguishable from those without based on area of the wetland, percent of the wetland that has emergent vegetation, percent of the wetland that is flooded by beaver or lake presence, and water pH. These results suggest that future work should focus on better understanding local scale characteristics distinguishing Bog Turtle wetlands, as current data resolution does not enable a SDM to be effective. iii DEDICATION I dedicate this thesis to Thomas Floyd and Grover Brown. This project all began six years ago with Thomas Floyd of the Georgia Department of Natural Resources giving me a chance to work with Bog Turtles. Thomas has not only been instrumental with the field work portion of the project but has become one of my most valued mentors and friends. No years of schooling could have taught me about what it really means to try and save an endangered species on-the-ground like working with Thomas did. I created some truly unpleasant field work for us, and although he didn’t have to, Thomas stuck with me through it all. I will forever be thankful that I had the incredible luck to work with such an amazing person. Grover Brown has also stuck with me throughout this project, helping out with three years of field work. No one else would be crazy enough to face the challenges we faced, all in the name of turtles. With no one else would I rather share a laugh, catch a turtle, or go on an adventure. His optimism and friendship are what help me through life’s hurdles. Finally I would like to say that everything I did was for Bog Turtles. I am grateful that I get a thesis out this work, but every second was really about trying to further Bog Turtle conservation. The blood, sweat, and tears would never have been worth it otherwise. They’re a tremendous annoyance to study, but I do not want to live in a world without them, and will gladly donate more blood, sweat, and tears to fight for a world that is more than just skyscrapers and pigeons. iv ACKNOWLEDGMENTS This project would not have been possible without the help of many people. First there are the people who have always believed in me and encouraged a young girl with big dreams: my advisor, Dr. Kyle Barrett, my Riverbanks Zoo family – especially Scott Pfaff and Kathy Vause, my friends at the Turtle Survival Alliance, and my parents – Johannes and Claudia Stratmann. Dr. John Maerz helped me initially design the project and take it to some cool places like Washington D.C. Dr. Nate Nibbelink and Dr. Jena Hickey helped guide the initial stages of the species distribution model work. I would also like to thank my committee members, Dr. Robert Baldwin and Dr. Michael Dorcas for their involvement. Then there are all the people who helped with field work, despite the fact that it often was not fun: Grover Brown, Briana Cairco, Maddy Fesite, David Hutto, Meaghan Miranda, Todd Pierson, Danielle Sexton, Claudia Stratmann, Kathy Vause, and Sydney Wells. I am also indebted to all the wonderful landowners who let me explore the wetlands on their property and taught me about the history of the area. Funding and support was generously provided by the Bern W. Tryon Funding for Southern Bog Turtle Population Research, Clemson University, the Georgia Department of Natural Resources, Riverbanks Zoo and Garden, and the South Carolina Department of Natural Resources. v TABLE OF CONTENTS Page TITLE PAGE .................................................................................................................... i ABSTRACT ..................................................................................................................... ii DEDICATION ................................................................................................................ iv ACKNOWLEDGMENTS ............................................................................................... v LIST OF TABLES ......................................................................................................... vii LIST OF FIGURES ...................................................................................................... viii CHAPTER I. LOCATING RARE HABITAT FOR A RARE SPECIES: EVALUATION OF A SPECIES DISTRIBUTION MODEL FOR BOG TURTLES (GLYPTEMYS MUHLENBERGII) IN THE SOUTHEASTERN UNITED STATES ................................................................................................... 1 Abstract .................................................................................................... 1 Introduction .............................................................................................. 2 Materials and Methods ............................................................................. 6 Results .................................................................................................... 15 Discussion .............................................................................................. 22 Literature Cited ...................................................................................... 28 II. DO HABITAT CHARACTERISTICS AND HISTORICAL DISTURBANCE PREDICT BOG TURTLE (GLYPTEMYS MUHLENBERGII) HABITAT OCCUPANCY AT THE FRINGE OF THEIR SOUTHERN RANGE?... ................................................................................................................ 36 Abstract .................................................................................................. 36 Introduction ............................................................................................ 37 Materials and Methods ........................................................................... 42 Results .................................................................................................... 56 Discussion .............................................................................................. 60 Literature Cited ...................................................................................... 64 vi LIST OF TABLES Table Page 1.1 Overview of the Maxent SDM’s classification success ............................... 17 2.1 Detection probabilities for occupied Georgia wetlands to calculate required trapping effort .......................................................................................